Types 1 and 2 diabetes and their complications are on the rise. There is a recognized lack in both approved complications-based therapies and established disease-specific biomarkers in diabetes complications, which significantly hinders clinical trials. This application focuses on the role of the receptor for advanced glycation endproducts (RAGE) and its cytoplasmic domain binding partner, mammalian form of diaphanous1, mDia1, which is essential for RAGE signaling as a fundamental therapeutic target for diabetic complications. To transform our discoveries from the bench to the development of therapies for diabetes complications, we performed a library screen and identified two lead series of small molecules that inhibit RAGE tail-mDia1 interaction with nM affinity and demonstrate efficacy in in vitro and in vivo experimental assays. We have developed novel RAGE and mDia1 floxed mice to probe their cell-specific contributions to diabetes complications. Our approach will involve testing the following specific aims: AIM 1 will seek to optimize the two lead compound series which block RAGE/mDia1 signaling by maximizing drug-like properties; Aim 2 will dissect the mechanisms by which RAGE-mDia1 signal transduction contributes to the pathogenesis of diabetic nephropathy; Aim 3 will dissect the mechanisms by which RAGE-mDia1 signal transduction contributes to the pathogenesis of ischemia-reperfusion (I/R) injury in the diabetic heart; and Aim 4 will dissect the mechanisms by which RAGE-mDia1 signal transduction contributes to diabetic complications via impaired resolution of inflammation, to serve as a springboard for the development of target engagement biomarkers. We have assembled a multi-disciplinary team with expertise in RAGE/mDia1 signal transduction and diabetes complications; structural biology and NMR spectroscopy; medicinal and computational chemistry; and bioinformatics/biostatistics to tackle the problem of therapies and target engagement biomarkers for diabetic complications.